This invention relates to cyclonic separator device for removing airborne particles, including solid and liquid, from contaminated air stream and, more particularly, to a novel apparatus for removing and recovering paint particles and solvents from the exhaust air.
There are three basic spray application techniques. The first one is air atomization where the coating particles are mixed with air stream ejected from the spray gun to the product to be coated. The second technique is airless atomization wherein the coating material is atomized and propelled by a hydraulic pressure. The third technique is electrostatic spraying wherein the coating material is atomized either by air or airless technique and the coating materials are deposited on the product by electrical attraction. Regardless of the spray technique used, a spray booth is commonly employed to prevent the stray of solvents and paint particles to the environment and the exposure of workers to the solvents and paint particles.
Present day spray booths are designed to provide a safe working place and to prevent polluting the atmosphere. Further, the use of spray booths will enhance the quality of the product being sprayed. In spray booths, it is necessary to maintain a steady and even flow of air through the booths. Constant air flow keeps the airborne paint particles and solvents, both of them are often toxic, away from the workers so that they will not inhale nor be exposed to toxic substances. These are usually required by Occupational Safety and Health Administration as well as by insurance carriers. The constant air flow also prevents the object that is being painted from forming drips or uneven finish. Moreover, environmental clean air standards require that the emissions from spray booths must not exceed a certain amount of particulates and solvents. Thus, the use of spray booths are usually required by the federal or state regulatory agencies, in particular, the Environmental Protection Agency.
To remove paint particulates and solvents from air exhausted from a spray booth, the common practice is to employ a replaceable fibrous filter which will trap the majority of the particulates and some of the solvent. These filters soon become clogged with sprayed particulates and require replacement. When the filters are clogged, the air flow through the booth is substantially reduced, thus decreasing the air flow past the worker inside the booth. Further, the air cleaning ability of the spray booth is greatly reduced and productivity is decreased because the system must be shut down to replace the filters. Moreover, these replaceable fibrous filters are expensive.
In U.S. Pat. No. 499,799 issued to Parkinson and Parkinson, a dust collector is disclosed. It is to be used in the treatment of grain where an air blast is employed for carrying off from the grain the dust. The device utilizes a series of chambers and passageways. Air accelerates through the passageways defined by S-shaped plates arranged in vertical rows, then the air becomes relatively dormant in the chamber allowing relatively heavy solid particles to drop out.
U.S. Pat. No. 768,415 issued to Wingrove discloses an oil interceptor to be used in ice making machines. The device has large surface of baffle-plate on which the ammonia gas and oil discharged from the compressor will strike. The oil will deposit on the surface and drain downward. The baffle-plate has a shape approximating a letter S, except instead of having a curved formation, the parts are angular.
U.S. Pat. No. 1,772,037 issued to Bradshaw teaches a fluid separator for separating the moisture and other impurities from the steam. The device uses the centrifugal effect on the flowing moisture so as to throw the liquid out of the current of gas against the baffles. The baffles increase in curvature as the inner or outlet ends are approached to enhance centrifugal effect. The baffles of the second annular row are curved in a direction opposite to the curvature of the baffles of the first annular row. The device also uses a plurality of complete stages of centrifugal separators.
In U.S. Pat. No. 3,077,714 issued to McIlvaine, a gas cleaner is taught. The device is a separator which causes intimate contact between the gas and the scrubbing liquid. The contaminant particles are entrapped in the liquid droplets which are then spun to form a film on the surface of a plate and discharged.
U.S. Pat. No. 3,236,031 issued to Bennett et al. teaches a wet dust separator. The device promotes the contact of whirling gas with a liquid so that dust particles thrown outwardly by the whirling action of the gas are entrapped by the liquid and removed from the gas along with the removal of the liquid.
U.S. Pat. No. 3,890,124 issued to Howes discloses a combination grease centrifugal separator and flame trap. The device is a box-like structure to be secured in the exhaust hood of a cooking range which extracts grease from the cooking fumes as they pass through the filter and prevents further propagation of any attendant flame at the filter. The grease and other exhaust particles are precipitated on the inner surfaces of the semicircular filter.
U.S. Pat. No. 4,061,478 issued to Hartwick discloses a self-cleaning smoke filter. The filter includes a channel with multiple longitudinal sides angularly disposed, an inlet port for receiving contaminated gaseous emissions, and an outlet port. The filter also contains spraying means for producing a cleansing spray inside the channel.
U.S. Pat. No. 4,239,513 issued to Paul teaches a separator device for separating out foreign particulates from a gas flow. The device uses wall plates to deflect a gas flow and to subject the same to centrifugal force so that the foreign particulates are collected on the wall plates. The device contains spirally curved S-shaped laminae to define passageways, at least a part of which has a cross-section which first narrows and then widens in the direction of fluid flow and which is also curved spirally first in one and then in the opposite direction. Nozzle means are arranged to feed moisture into the fluid flow to assist wet separation. The device relies on, firstly, narrowing acceleration paths; secondly, the introduction of water; and, lastly, reversal of flow to form a secondary vortex and pull a film of fluid back into air suspension to mix with the solids and again be deposited on the wall plates as gas travels through the exit passage.
U.S. Pat. No. 4,321,064 issued to Vargo teaches a filter apparatus for separating suspended particles from a fluid. The filter contains a flat sheet, a corrugated sheet adhered to the flat sheet, a first array of parallelly spaced orifices formed in the flat sheet, and a second array of parallelly spaced orifices formed in the sheet. The orifices in the first array are disposed laterally in spaced relationship from orifices in the second array. Further, orifices in the first array communicate with orifices in the second array through corrugation in the corrugated sheet.
In U.S. Pat. No. 4,328,012 issued to Telchuk, Jr. et al., an air washer/scrubber is disclosed. The device flows opposed sheets of water over a subfloor of a paint spray booth down the steeply inclined walls of a shallow, V-shaped slot, and against upturned ledges along the inner edges of the slot walls. These ledges kick the water from each of the opposed slot walls upwardly and inwardly to from a curtain of water to cover the slot opening. When the paint-laden air is pulled into the slot and accelerated through this curtain of water, the air and water are intermixed and, consequently, removes the paint particles.
U.S. Pat. No. 4,483,698 issued to Kuchenthal et al. teaches an apparatus for paint mist removal. This device vigorously mixes the exhaust air with the washing liquid whereby the paint particles are absorbed onto washing liquid droplets which can be removed.
U.S. Pat. No. 4,515,073 issued to Dorsch et al. discloses an air scrubbing system. The apparatus includes a sub-floor flooded with a flowing scrubbing fluid and a scrubbing fluid spray source with conduit means having baffles that cause the air and the fluid spray to flow in a direction-reversing serpentine path. The contaminated air passes through the scrubbing fluid multiple of times so that the particulate matter can be removed.
U.S. Pat. No. 4,608,064 issued to Napadow teaches a multi-wash spray booth. The device uses a multiple of water washes in the air cleaning section of the spray booth.
U.S. Pat. No. 4,704,952 issued to Johnson et al. discloses an apparatus for applying paint. The invention is directed to a wet scrubber for use in a downdraft type paint spray booth in which the air leaving the lower ends of the outlet structures in the wetted subfloor is caused to undergo a sharp directional change, thereby throwing off water in the immediate vicinity of the scrubber discharge. The paint-laden water is collected and directed to a treatment facility.
German Patent Description No. 1,122,498 teaches a device for the separation of finely distributed liquid out of a gaseous transportation medium. The transportation medium is partitioned into thin layers by a number of horizontally positioned chambers which run parallel to one another, formed by guide tin plates and bypassed twice by about 180.degree.. The device provides for the guidance sheet metal plates being concavely bent against one another in both bypass areas, so that these plates form a widening and again tapering path of turbulence.
Emission standards are set very high today. While some prior art devices may suggest various techniques, such as spraying water in a spray booth to trap the paint particulates and solvents, they often do not meet today's rigorous requirements. Consequently, many of the spray booths which were designed earlier no longer can meet the new rigorous emission standards. Further, prior art devices are not well suited for collecting stray paints and solvents for re-use.
Accordingly, there is a need for an filter or baffle system that does not have to be replaced often and that will efficiently remove airborne particles, including solid and liquid, from exhaust air so that the air emitted to the atmosphere will not pollute the surrounding areas. Moreover, there is a need to recover for re-use strayed paints and solvents.